Basic Troubleshooting Procedures

Basic Troubleshooting Procedure

Customer Problem Analysis Check Sheet

Basic Inspection Procedure: Resistance Measurement Conditions for Electronic Components. Measured resistance may be high or low when the engine is hot after starting. Therefore, all resistances must be measured at ambient temperature (20 °C, 68°F), unless otherwise specified.Intermittent Problem Inspection Procedure: Sometimes the most difficult case in troubleshooting is when the Symptom occurs but does not recur during testing. An example is when the problem appears only on a cold vehicle but does not appear when warm. In this case, the technician must carefully review the Customer Problem Analysis Sheet and recreate (simulate) the environment and conditions that existed when the vehicle had the problem.

1. 1
   Clear the Diagnostic Trouble Code (DTC).
2. 2
   Inspect the connector and check the terminals for poor contact, loose wires, bent, broken or corroded contacts, then make sure all connectors are always securely fastened.

   

3. 3
   Lightly shake the connector and wiring harness vertically and horizontally.
4. 4
   Repair or replace the faulty component.
5. 5
   Confirm that the problem is resolved by performing a road test.
6. 6
   Sensors and Actuators: Gently tap the sensors, actuators or relays with a finger.
7. 7
   Connectors and Harness: Lightly shake the connector and wiring harness vertically, then horizontally.
8. 8
   Heat components suspected of causing the malfunction with a hair dryer or other heat source.
9. 9
   Spray water on the vehicle to simulate a rainy day or high humidity condition.
10. 10
    Turn on all electrical systems to simulate excessive electrical load (radio, fans, headlights, rear window defogger, etc.).
11. 11
    Connector Handling

    A.	Never pull on the wire harness when disconnecting connectors.

    B.	When disconnecting a connector with a lock, press or pull the lock lever.

    C.	Listen for a click when connectors lock. This sound indicates that they are securely locked.

    D.	When using a tester to check continuity or measure voltage, always insert the tester probe from the wire harness side.

    E.	Check the waterproof connector terminals from the connector side. Waterproof connectors cannot be checked from the harness side.

12. 12
    Connector Checkpoints

    A.	While the connector is connected: Hold the connector and check the connection condition and locking efficiency.

    B.	When the connector is disconnected: Check for a missing terminal, crimped terminal, or broken core wire by lightly pulling the wiring harness. Visually check for rust, contamination, deformation, and bending.

    C.	Check the terminal tightening condition: Insert a spare male terminal into the female terminal, then check the tightening condition of the terminal.

    D.	Lightly pull the individual wires to make sure each wire is secured in the terminal.

13. 13
    Connector Terminal Repair Method

    A.	Clean the contact points using compressed air and/or a cloth.

    B.	If the contact pressure is abnormal, replace the female terminal.

14. 14
    Before removing the wiring harness, check the position of the wiring harness and clamps so that it can be restored correctly.
15. 15
    Check that the wire harness is not twisted, stretched or loose.
16. 16
    Check whether the temperature of the wiring harness is abnormally high.
17. 17
    Check whether the wiring harness rotates, moves, or vibrates against a sharp edge of a part.
18. 18
    Check the connection between the wiring harness and any installed part.
19. 19
    If the wiring harness covering is damaged, secure, repair, or replace the harness.
20. 20
    Open Circuit Procedures

    A.	Continuity Check

    B.	Voltage Check

    If an open circuit occurs (as shown in [FIG. 1]), it can be located by performing Step 2 (Continuity Check Method) or Step 3 (Voltage Check Method) as shown below.

    

21. 21
    Continuity Check MethodSpecification (resistance): 1 Ω or less → Normal circuit; 1 MΩ or more → Open circuit

    A.

    Disconnect connectors (A) and (C), and measure the resistance between connector (A) and (C), as shown in [FIG. 2]. In [FIG. 2], the measured resistance of lines 1 and 2 is above 1 MΩ and below 1 Ω, respectively. Specifically, the open circuit is line 1 (line 2 is normal). To find the exact open point, check the sub-section of line 1 as described in the following step.

    B.

    Disconnect connector (B) and measure the resistance between connector (C) and (B1), and between (B2) and (A), as shown in [FIG. 3]. In this case, the measured resistance between connector (C) and (B1) is above 1 MΩ, and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).

22. 22
    Voltage Check Method

    A.	With each connector still connected, measure the voltage between chassis ground and terminal 1 of each connector (A), (B), and (C), as shown in [FIG. 4]. The measured voltage of each connector is 5 V, 5 V, and 0 V, respectively. Therefore, the circuit is open between connector (C) and (B).

23. 23
    Short to Ground Check Method

    A.	Continuity Check with Chassis Ground

    If a ground short occurs, as shown in [FIG. 5], the fault point can be located by performing Step 2 (Continuity Check Method with Chassis Ground), as shown below.

    

24. 24
    Continuity Check Method (with Chassis Ground)Specification (resistance): 1 Ω or less → Short to ground; 1 MΩ or more → Normal circuit

    A.

    Disconnect connectors (A) and (C), and measure the resistance between connector (A) and chassis ground, as shown in [FIG. 6]. The measured resistance of lines 1 and 2 in this example is below 1 Ω and above 1 MΩ, respectively. Specifically, the ground short is line 1 (line 2 is normal). To find the exact fault point, check the sub-section of line 1 as described in the following step.

    B.

    Disconnect connector (B) and measure the resistance between connector (A) and body ground, and between (B1) and chassis ground, as shown in [FIG. 7]. The measured resistance between connector (B1) and chassis ground is 1 ohm or less. There is a short to ground between terminal 1 of connector (C) and terminal 1 of connector (B1).

25. 25
    Connect the positive (+) probe of the voltmeter to the end of the wire (either on the connector or switch side) closest to the battery.
26. 26
    Connect the negative lead to the other end of the wire (or the other side of the connector or switch).
27. 27
    Operate the circuit.
28. 28
    The voltmeter will show the voltage difference between the two points. A difference or drop of more than 0.1 V (50 mV in a 5 V circuit) may indicate a problem. Check the circuit for loose or dirty connections.

    

● Simulate Vibration ● Simulate Heat ● Simulate Water Spray ● Simulate Electrical Load Connector Inspection Procedure Harness Inspection Procedure Electrical Circuit Inspection Procedure ● Check for Open Circuit ● Check for Short Circuit ● Voltage Drop Test This test checks the voltage drop across a wire or connection or switch. Symptom Troubleshooting Table

Main Symptom	Diagnostic Procedure	Also check
Cannot Start (Engine does not crank)	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Test the starter motor. (Refer to Engine Electrical System - "Starter") 3 Inhibitor switch (A/T) or clutch start switch (M/T)
Cannot Start (Incomplete combustion)	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4 Troubleshoot the immobilizer system. (Refer to Body Electrical System - "Immobilizer System") (If the immobilizer lamp is flashing)	Trouble Code Low compression Intake air leaks Slipping or broken timing belt Contaminated Fuel
Hard to Start	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Inspect the ECTS and circuit. (Refer to Engine Control System - "ECTS") 4 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System")	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Poor Idling (Rough, unstable or incorrect idle)	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Check the injector. (Refer to Engine Control System - "Injector") 3 Check the long-term fuel trim and short-term fuel trim. (See CUSTOMER DATA FLOW) 4 Check the idle air control circuit (check DTC). 5 Inspect and test the electronic throttle body. (Refer to Engine Control System - "ETC") 6 Inspect the ECTS and circuit. (Refer to Engine Control System - "ECTS")	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Engine Stalls	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the idle air control circuit (check DTC). 4 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 5 Check the CKPS circuit (check DTC)	Trouble Code Intake air leaks Contaminated Fuel Weak ignition spark
Poor Driveability (Surging)	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Inspect and test the electronic throttle body. (Refer to Engine Control System - "ETC") 3 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4 Inspect the ECTS and circuit. (Refer to Engine Control System - "ECTS") 5 Check the exhaust system for possible blockage 6 Check the long-term fuel trim and short-term fuel trim. (See CUSTOMER DATA FLOW)	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Knock	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Inspect the engine coolant 3 Inspect the radiator and the electric cooling fan. 4 Inspect the spark plugs. (Refer to Engine Electrical System - "Spark Plug")	Trouble Code Contaminated Fuel
Poor Fuel Economy	Check the customer's driving habits. Is the air conditioner operating continuously or is the defroster mode on? Is the tire pressure correct? Is the vehicle carrying an excessively heavy load? Is the vehicle accelerating too hard or too frequently? 1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Check the injector. (Refer to Engine Control System - "Injector") 3 Check the exhaust system for possible clogging. (Refer to Engine Mechanical System - "Exhaust Manifold") 4 Inspect the ECTS and circuit. (Refer to Engine Control System - "ECTS")	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Hard to Refuel (Overflow during refueling)	1 Inspect the canister close valve. (Refer to Engine Control System - "CCV"). 2 Inspect the fuel tank hose/tube. Is it pinched, kinked, or blocked? Filler hose is torn. 1 Inspect the fuel tank vapor vent hose between the canister and the fuel tank air filter. (Refer to Emission Control System - "Evaporative Emission Control System") 2 Inspect the canister. (Refer to Emission Control System - "Canister")	Malfunctioning fuel nozzle at gas station (if this problem occurs at a specific gas station during refueling).